Sudden Hearing Loss with Vertigo Portends Greater Stroke Risk Than Sudden Hearing Loss or Vertigo Alone

Abstract

Background: Because it is unknown whether sudden hearing loss (SHL) in acute vertigo is a "benign" sign (reflecting ear disease) or a "dangerous" sign (reflecting stroke), we sought to compare long-term stroke risk among patients with (1) "SHL with vertigo," (2) "SHL alone," and (3) "vertigo alone" using a large national health-care database.

Methods: Patients with first-incident SHL (International Classification of Diseases, Ninth Edition, Clinical Modification [ICD-9-CM] 388.2) or vertigo (ICD-9-CM 386.x, 780.4) were identified from the National Health Insurance Research Database of Taiwan (2002-2009). We defined SHL with vertigo as a vertigo-related diagnosis ±30 days from the index SHL event. SHL without a temporally proximate vertigo diagnosis was considered SHL alone. The vertigo-alone group had no SHL diagnosis. All the patients were followed up until stroke, death, withdrawal from the database, or current end of the database (December 31, 2012) for a minimum period of 3 years. The hazards of stroke were compared across groups.

Results: We studied 218,656 patients (678 SHL with vertigo, 1998 with SHL alone, and 215,980 with vertigo alone). Stroke rates at study end were 5.5% (SHL with vertigo), 3.0% (SHL alone), and 3.9% (vertigo alone). Stroke hazards were higher in SHL with vertigo than in SHL alone (hazard ratio [HR], 1.93; 95% confidence interval [CI], 1.28-2.91) and in vertigo alone (HR, 1.63; 95% CI, 1.18-2.25). Defining a narrower window between SHL and vertigo (±3 days) increased the hazards.

Conclusions: The combination of SHL plus vertigo in close temporal proximity is associated with increased subsequent stroke risk over SHL alone and vertigo alone. This suggests that SHL in patients with vertigo is not necessarily a benign peripheral vestibular sign.

Keywords: Sudden hearing loss; diagnosis; dizziness; vertebrobasilar stroke; vertigo.

Figure 1

Study population derivation (clinical subgroups and temporal relationship between SHL and vertigo). (A) Venn diagram showing the study populations for the primary analysis (wide window definition [±30 days] for “SHL with vertigo”). Note that the Venn diagram areas are not precisely proportional to the study populations. (B) Histogram (rendered as a line graph) of the SHL population arranged by time between SHL and vertigo events in days. Positive numbers reflect SHL followed by vertigo and negative numbers, the reverse. Case numbers were highest when the interval between SHL and vertigo diagnosis was ±1 day, and precipitously declined within ±3 days, leveling out by ±30 days. This pattern suggests that SHL and vertigo, when they co-occur, tend to cluster together as related events, rather than random, unassociated events. This graph does not distinguish between those with peripheral and central vestibular disorders. Abbreviation: SHL, sudden hearing loss.

Figure 2

Stroke-free survival using Kaplan–Meier analysis. (A) Kaplan–Meier curve showing stroke-free survival for SHL with vertigo and SHL alone. Case numbers of noncensored observations are listed above the x-axis. There is a statistically significant difference in stroke-free survival, lower among those with SHL with vertigo (log-rank test: P = .001). (B) Kaplan–Meier curve showing stroke-free survival for SHL with vertigo and vertigo alone. Case numbers of noncensored observations are listed above the x-axis. There is a statistically significant difference in stroke-free survival, lower among those with SHL with vertigo (log-rank test: P = .003). Abbreviation: SHL, sudden hearing loss.